"I'd like something really fast and which feels like a slalom board, not a formula but would an Isonic 133 or 122 be suitable for me with 7,8 and 9,0 ?"

Given your weight, I would think that the 2008 iS144 would be your optimum pick. It virtually the same outline shape as the iS133, but its added volume specifically targets heavyweights for light wind slalom.

Regarding your concern that a board like the iS144 is too close to formula, I think that it's important to remember that the iS144 will be focused more on reaching rather the upwind/downwind attitude of formula.

In light of the fact that you pointed out that a 2007 iS145 was board available in your area, you might want to query a bit more about the pluses and minuses between the iS144 and the iS145 before making your decision.